Final answer:
The statement is false; muscle synergy refers to the cooperation of muscles during movement, not one muscle contracting to stop the action of another which is the role of antagonist muscles.
Step-by-step explanation:
The statement that true synergy occurs when a muscle contracts to stop the secondary action of another muscle is largely false. Muscle synergy usually refers to the cooperation of multiple muscles working together to perform a movement. However, what is being described more closely aligns with the role of an antagonist muscle. An antagonist muscle contracts to oppose the action of the agonist, or prime mover. During synergistic movement, muscles do not act to stop the action of another but to aid in creating a smooth and coordinated movement.
For example, when flexing the forearm, the biceps brachii acts as the agonist muscle causing the movement, while the triceps brachii acts as the antagonist to control the motion and ensure the arm doesn't move too quickly or overextend. The synergistic muscles, such as the brachialis and brachioradialis, assist the biceps in the flexion of the forearm. This example also explains the phenomenon of recruitment, where more motor units are activated to increase the strength of muscle contraction.